Proton-Dependent Monomer - Oligomer Interconversion of Metal Complexes

摘要

Metal-directed self-assembly processes like formation of catenanes and helicates by spontaneous assembly of oligo-2,2'-bipyridine strands and metal ions have attracted much interest in recent years. As a further development of this fascinating area ofsupramolecular chemistry, metal complexes capable of reversibly interconverting between monomers and self-assembled oligomers by inputting external information (afforded, for example, by protons, electrons, or photons) would be of the utmost interest. Indeed, they could afford new functional materials with a switching ability, and in more specific cases the ability to sequester/release guest molecules or ions according to the delivered external information, provided the polydentate ligand is properly designed to induce the formation of a monomeric species that exhibits the following building block characteristics : a) potential donor ab'lity at a suitable external site of the chelating ligand; b) potential acceptor ability at a vacant or substitutablemetal coordination site; c) building process from monomeric into oligomeric species and reverse dismantling process both triggered by appropriate external signals; d) for the more specific case of sequestering/release of guest molecules or ions, presence of one or more cavities in the resulting oligomeric molecular structure, cooperatively determined by the steric restriction provided by the ligand frame and the coordination geometry required by the metal ion.